Hi Envisage Me,
To make sure we pay the correct fee amount you should only put on it the amount you are being charged for your 60 credits. If you want to increase the fee amount later in the year it's really easy to do you would just go onto your online account then select the 'change your application' link then you would see a link for a paper Change of Circumstances (CO2) form that you can print off and complete and send into us.
On the form you would update the fee amount the Open University are charging you to the total amount of fees required for the academic year based on the number of credits you are doing. Once processed we can increase your fees to the correct amount and a new Notification of Entitlement letter would be sent to you to confirm this.